Paraffin-microcrystalline wax composition



United States Patent 3,379,550 PARAFFIN-MlCROCRYSTALLINE WAX COMPOSITION John Podlipnik, Palos Heights, Ill., assignor to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed June 26, 1964, Ser. No. 378,449

Claims. (Cl. 106-270) This invention relates to wax compositions for coating of paper and paperboard cups and other containers. The compositions impart a high degree of rigidity to the container along with a smooth, non-glossy, satin-like finish.

Petroleum waxes are used extensively for coating of paper and paperboard cups used in the dispensing of soft drinks, ice cream sodas and malts, etc. Among other things, the Wax serves to strengthen and waterproof the cup. The strength is of particular importance in dispensing of ice cream sodas and malts since in many cases the cup serves to hold the contents during blending, and the nature of the contents is such that any loss in strength due to penetration of water into the board is undesirable. The Wax should be such as to result in a smooth, continuous, satin-like finish. In addition, the melting point and blocking temperature of the coating should be sufficiently high to prevent sticking of the wax-coated cups when they are nested.

Many of the waxes presently used as cup coatings fail to provide a high degree of strength along with a smooth finish. Attempts to improve smoothness and strength through the use of polymers such as polyethylene and various resins have been unsuccessful. While such additives provide smooth continuous coatings they do not give the desired rigidity, and, in fact, they many times adversely affect rigidity. Furthermore, they are costly and increase viscosity which adversely affects machine performance.

Ithas now been found that by blending a certain narrow range approxim ately 138 145 F. melting point parafiin Wax with about 5 to by weight of a particular micro'crystalline wax, a paper and paperboard cup coating composition is produced which provides outstanding rigidity and excellent cup appearance.

The paratfin wax should be a relatively narrow range material composed of essentially straight chain paraffins. It should have the following approximate properties:

Refractive index at 80 C 1.4294432 l0-90% distillation range at 760 mm, F. 700-950 By the 10 to 90% distillation range it is meant that the actual 10 to 90% distillation range of the wax is within the range of about 700 to 950 F., preferably within about 725 to 925 F., often with a 10 to 90% spread of about 100 to 225 F. unit Within the ranges cited. The paraffin Wax can be prepared by conventional phenol extraction, methyl ethyl ketone dewaxing, and methyl ethyl ketone deoiling of a waxy petroleum distillate having an appropriate distillation range.

'Har-aflin Waxes Wh'ose properties fall outside of these ranges are unsatisfactory. For example, if the viscosity is above about 42 SSU at 210 F this leads to difiiculties in machine performance and higher wax consumption. Waxes with melting points below about 138 F. generally have too low blocking points for this application. Broad range waxes having wider distillation ranges do not provide desired rigidity and adversely aiiect machine performance. Tests on a blend in which a broad range wax Melting point, F. ASTM D'127 -200 Penetration at 77 F., 100 gms. ASTM (D- 1321 Viscosity at 210 F., SSU

Microcrys talline Waxes which meet these requirements can be used as the minor constituent of the wax composition. The microwax preferably can be a tank bot-tom microcryst alline wax which is the high melting point wax obtained by the refining of the waxy materials which settle out of crude oil during storage or the high melting point microcrystalline waxes in this range prepared by the conventional solvent deoiling of petrol'atum. The properties and the concentration of the miorocrystalline Wax blended with the paraffin wax component are important. Microwaxes which do not meet the required properties fail to provide the desired satin-like coating and rigidity. Employment of less than about 5% of the micro'crystalline wax also fails to give the desired smooth, non-glossy coating. Use or greater than about 10% by weight of the microcrystalline wax tends to embri't tle the wax and provides a fin al blend which leads to excessive build up on machine parts, high wax consumption, and possible ditficulties with settling of microwax in storage tanks. The

r preferred microwaxes are the tank bottom micro'cryst alline Waxes having a melting point of about to F. (ASTM Df127) and when blended with the preferred parafiin wax, i.e. of about 142/ 144 F., melting point, may, with advantage be added in an amount of about 6% by weight. The wax blends of the invention have the following approximate properties:

Penetration at 77 F... Refractive Index at 80 C 8 6-11 1. 4310 1. 4290-1. 432 Cloud Point, F 159 155-165 Without the defined paraifin wax and microcrystalline Waxes and in the defined proportions these properties are not met.

Although the wax of the present invention exhibits its greatest advantage with respect to the doating of paper and paperboard cup or similar containers, it can be used as well in the coating of other paper and paperboard articles.

The following example is included to further illustrate the present invention.

Example Several waxes and wax blends identified in the table below were used to coat paper cups in the laboratory and on commercial equipment.

The procedure used in the laboratory to coat the sample cups consisted of immersing tared 16 oz. cups in the wax sample at 205 F. for 15 seconds followed by draining and solidification in room temperature air. During draining the cup is held upside down until the coating solidifies. Consumption is determined by weighing the waxed cups and determining wax pickup.

Commercial coatings were also performed on a spray A comparison of blend 1 with blends 2 and 3 and a coating machine in which the wax is sprayed at about comparison of blend 6 with blend 7 show the need to 200 F. on a cup roating on a spindle. The sprayed cup add at least of a 180-200 F. melting point microrides upside down through a heat tunnel after which it is crystalline wax to obtain a smooth, satin, non-glossy apcooled with room temperature air. 5 pearance. The high rigidity (as measured by the force re- All of the coated oups were evaluated as to appearance quired to crush the cups) provided by the narrow melting and several coated cups were subjected to a crush test. An point range paraffin wax of the invention is shown by comuncoated cup was also tested for comparison. Two crush paring blends 3 and 4 with blend 7. Note that the melting tests were employed, the vacuum crush test and the point and other physical properties of blend 7 were almost S ua ho t test, 10 identical to those of blend 4, yet the rigidity provided by In the vacuum crush test the wax cup is placed upside blend 7 was unacceptable. It appears from these results down on the center neck of a three necked flask, and the that it is the pres c of the low melting, relatively low lip of the cup sealed to the flask using silicone grease. bo ling 129 F. melting point and high melting point Vacuum is applied to the flask and the cup at a constant waxes that lead to less rigidity with blend 7. rate of evacuation, and the reduction in pressure measured t IS Claimed:

with a manometer containing C431 At a certain point 1. A Wax composition consisting essentially of a the cup is unable to withstand outside air pressure and Straight chain parafiin wax having amelting point (ASTM collapses breaking the vacuum. The manometer reading of about 138 to a Viscosity at is measured and recorded as the vacuum crush value in of about 38 to 42 a P tion at 77 F. (ASTM centimeters of CCl.,,. D-1321) of about 7 to 11; a refractive index at 80 The Squashometer test consists of applying a force at C. of about 1.429 to 1.432 and a 10-90% distillation a constant rate at two diametrically opposite points of range at 760 mm. in the range of about 700 to 950 F., the cup about 2 inches from the bottom of the 16 oz. and about 5 to 10% y Weight of a microcl'ystauine cup. The total force required to crush the cup is measured Wax having a melting point (ASTM D-127) of about and called the Squashometer value. 180 to 200 F.; a penetration at 77 F. (ASTM D-1321) The waxes and wax compositions evaluated and the of about 2 to 8 and a viscosity at 210 F. of about test results are summarized in the table: to SSU.

TABLE-PROPERTIES OF PAPER CUPS COATED WITH VARIOUS IVAXES Wax Identity 1 2 3 4 5 Base Waxes:

129 F. M.P. Paraflin Wax 143 M.P. Peraflin Wax 100-- 94 153 F. M.P. Paraflin Wax 194 F. M.P. Tnnk Bottoms Microwax 4 5... 7.

Laboratory Coated 16 oz. Cupsz' Consumption, Lbs/1,000 cups Vacuum Crush cm. 010014.-..

Appearance:

Gloss. Some gloss. None.. None Orange Pronounced.. ight -.do .do 0. Feel.. Rough, grainy Slightly grainy..-. Smooth, satin.... Smooth, satin..... Smgpth,

so u. Commercially Coated 16 oz. Cups:

Consumption, Lbs/1,000 cups 11.3 Squashometer Crush, Grams 1,525 Appearance:

Gloss None Orange Peel.

e Physical Properties:

Melting Point, F. ASTM D-87 143.5 143.2

Melting Point, F. ASTM D-127- Viscosity at 210 F., SUS Penetration at 7 7 F Refractive Index at 80 C 10-90% Distillation Range at 760 mm.

Wax Identity 6 7 8 9 Unwaxed Cup Base Waxes:

129 F. M.P. Paraflin Wax 20 19 143 F M P. Paraflin Wax.. 45. 153 F. M.P. Paraifin Wax 35.

194 F. M.P. Tank Bottoms Microwax Laboratory Coated 16 oz. Cups? Consumption, Lbs/1,000 cups Vacuum Crush, cm. of C 014 Appearance:

Gloss.-. Very slight None Some gloss Orange Peel Moderate.-. do Prono Feel Slightly rough...-- Smooth, satin.- Rough, grainy Commercially Coated 16 oz. Cups:

Consumption, Lbs/1.000 cups 10.9-11.1 Squashometer Crush, Grams 1,3001,400 Appearance:

G1oss.. None Orange Peel do Feel Smooth, satin Physical Properties:

Melting Point, F. ASTM D-87 143 143 153 Melting Point, F. AS'IM D127.- 194 Viscosity at 210 F., SUS Penetration at 77 F-.

Refractive Index at 80 C 10-90% Distillation Range at 760 mm.,

Cups seated at 205 F., 15 seconds dip in wax bath, cooled in room temperature air.

5 6 2. The composition of claim 1 wherein the parafiin References Cited WaX a point about 142 to 14-4 F. and the rnmrocrystallme wax 1s a tank bottom nncrocrystalline Wax having a melting point of about 190 to 195 F.

3.Th 't' flzh 'thtkbtt ,1 em

ecomposl calm w erem e an 0 0m 5 3,128,241 4/1964 PodliPnik microcrystalline wax is present in an amount of about 6% by weight. I

4. A paper cup coated with the composition of claim 1. ALEXANDER BRODMERKEL Pnmary Exammer' 5. A paper cup coated with the composition of claim 2. T. MORRIS, Assistant Examiner. 

1. A WAX COMPOSITION CONSISTING ESSENTIALLY OF A STRAIGHT CHAIN PARAFFIN WAX HAVING A MELTING POINT (ASTM D-87) OF ABOUT 138 TO 145*F.; A VISCOSITY AT 210*F. OF ABOUT 38 TO 42 SSU; A PENETRATION AT 77*F. (ASTM D-1321) OF ABOUT 7 TO 11; A REFRACTIVE INDEX AT 80* C. OF ABOUT 1.429 TO 1.432 AND A 10-90, DISTILLATION RANGE AT 760 MM. IN THE RANGE OF ABOUT 700-950*F., AND ABOUT 5 TO 10% BY WEIGHT OF A MICROCRYSTALLINE WAX HAVING A MELTING POINT (ASTM D-127) OF ABOUT 180 TO 200*F.; A PENETRATION AT 77*F. (ASTM D-1321) OF ABOUT 2 TO 8 AND A VISCOSITY AT 210*F. OF ABOUT 60 TO 90 SSU. 